Sense Organs Flashcards
vital to the integrity of personality and intellectual function
sensory input
structure specialized to detect a stimulus
sensory receptor
change in environment
stimulus
leads to hallucinations
sensory deprivation
general purpose of sensory receptor is
transduction
conversion of one form of energy to another
transduction
activation of sensory receptors result in
receptor potential
small local electrical charge on a receptor cell
receptor potential
subjective awareness of the stimulus
sensation
interpretation of meaning of a particular stimulujs
perception
4 kinds of information
modality, location, intensity, duration
type of stimulus or sensation it produces
modality
encoded by which nerve fibers are firing
location
area within which a sensory neuron detects stimuli
receptive field
intensity determined by
sensitivity, recruitment, firing frequency
how long stimulus lasts
duration
if a stimulus is prolonged firing of the neuron gets slower over time
sensory adaptation
adapt rapidly; generate a burst of action potentials when first stimulated then quickly reduce or stop signaling even though the stimulus continues
phasic receptors
adapt slowly; generate nerve signals more steadily throughout presence of stimulus
tonic receptors
body position, muscle tension and joint motion
proprioceptors
pain receptors
nociceptors
respond to mechanical forces
mechanoreceptors
monitor blood pressure
baroreceptors
respond to temperature changes
thermoreceptors
respond to chemicals in solution
chemoreceptors
respond to light
photoreceptors
respond to pain causing stimuli
nociceptors
sensitive to stimuli arising from outside the body
exteroceptors
receive stimuli from internal viscera
interoceptors
sense the position and movements of the body
proprioceptors
receptors are widely distributed
general somatosensory senses
receptors are limited to head
special senses
nerve endings that lack connective tissue wrappings: i.e free nerve endings, tactile discs, hair receptors
unencapsulated
wrapped by glial cells/connective tissue; wrapping enhances sensitivity or selectivity of the response
encapsulated
discomfort caused by tissue injury or noxious stimulation
pain
lost in diabetes mellitus
diabetic neuropathy
arises from the skin, muscles, and joints
somatic pain
arises from the viscera
visceral pain
most potent pain stimulus known
bradykinin
pain signals from head
travel in cranial nerves V, VII IX, and X to medulla
pain signals from neck down
spinothalamic tract, spinoreticular tract gracile fasciculus
most significant pain pathway; carries most somatic pain signals
spinothalamic tract
carries pain signals to reticular formation; activate visceral, emotional, and behavioral reactions to pain
spinoreticular tract
carries signals to the thalamus for visceral pain
gracile fasciculus
pain in viscera often mistakenly thought to come from a somatic body region
referred pain
pain relieving mechanism of CNS; just beginning to be understood
analgesic
internally produced opium like substances
endogenous opiods
analgesic oligopeptides with 200 times the potency of morphine
enkephalins
neuropeptides
endorphins and dynorphins
stops pain signals at the dorsal horn of the spinal cord
spinal gating
